Microsoft Corp.s fix for the Windows Metafile vulnerability will be shipped Thursday as a critical, out-of-cycle update.
Reversing an earlier decision to release the patch on Jan. 10., the software maker announced that strong customer demand for an emergency update triggered the shift in plans.
The fixes have been included in the MS06-001 bulletin and apply to users of Windows 2000 SP4, Windows XP SP1 and SP2, and Windows Server 2003 SP1.
There are no free patches available for computer users running Windows 98, Windows ME and pre-SP4 versions of Windows 2000, since those versions of the operating system are out of mainstream product support.
Even as it admitted that active exploits and strong customer demand forced the early release of the update, Microsoft continued to insist that the attacks are limited and are being mitigated by its efforts to shut down malicious sites hosting the rigged WMF image files.
Johannes Ullrich, chief technology officer at the SANS ISC (Internet Storm Center), remained critical of Microsofts handling of the issue. "Weve been working with them all week, feeding them exploits, trying to convince them that this is a very high-risk threat that was growing worse everyday, but they just werent getting it," Ullrich said in an interview with eWEEK.
"We finally got through to them that this required an emergency patch and Im happy they decided to go out-of-cycle," he said.
Ullrich said the ISC provided blow-by-blow evidence to Microsoft that legitimate, high-traffic Web sites were being used to deliver the exploits without any user interaction.
Knoppix STD, which delivers a collection of Linux-based security tools, was hijacked by malicious hackers and redirected to a site serving up rigged WMF images, Ullrich said.
"A lot of law enforcement people got infected and it look a long time to get that site shut down. Microsoft knew this all along," Ullrich said. "Even today, they are claiming that user interaction is required, but they know otherwise."
"We sent them screenshots just today, showing them step by step how the exploit worked without any interaction. It took so long to get this through to them. We were convinced it was more serious than they were letting on and thats why we made such a big deal out of it," Ullrich said.
The SANS ISC has been criticized in some quarters for overblowing the threat, but Ullrich is adamant that his volunteers made the right call and said he feels vindicated by Microsofts decision to ship an emergency patch.
The software maker still plans to release two separate security bulletins as part of the regularly scheduled Patch Tuesday on Jan. 10. Both will be rated "critical," the companys highest severity rating.
The two bulletins will cover holes in Microsoft Windows, Microsoft Exchange and Microsoft Office.